Dr. Eran Perlson and researchers in lab at Tel Aviv University Dr. Eran Perlson and researchers in lab at Tel Aviv University Dr. Eran Perlson, right, works with his team of researchers in his lab at Tel Aviv University. (Photo courtesy Eran Perlson)

Scientists discover how rabies takes a ‘fast train’ to the brain

Research could lead to new treatments for diseases like Alzheimer's, Parkinson's and ALS.

Scientists have known for many years that the rabies virus attacks the central nervous system quickly and efficiently, and that the speed of its progression makes it extremely life-threatening. But until now, it wasn’t clear how this fast travel occurs. A recent study used an innovative form of cell imaging to track the path that the virus takes and illuminate how it can move so rapidly to the brain and other vital organs.

This new understanding of how rabies is transported to the brain could help open up avenues for treatment – scientists might, for instance, be able to send therapeutic drugs through the same route.

"Understanding the basic machinery of rabies virus transport could open the door for manipulating this delicate transport system,” Dr. Eran Perlson of Tel Aviv University told From The Grapevine. “Not only may this lead to the ability to slow down rabies’ progression inside nerve cells, but it might also help researchers who develop new drug delivery methods into the nervous system.”

Such treatments could potentially be applied to other neurodegenerative diseases, such as Alzheimer’s, Parkinson’s and ALS, Perlson said.

The research, led by Perlson and his colleagues at TAU’s Sackler Faculty of Medicine and Sagol School of Neuroscience, was conducted in collaboration with the Friedrich Loeffler Institute in Germany. The team published their findings in PLOS Pathogens.

"Rabies not only hijacks the nervous system’s machinery, it also manipulates that machinery to move faster," Perlson said. 

The virus uses neuron protrusions called axons, responsible for transmitting electric impulses and small molecules, to enter neurons faster than other molecules can, including the ones responsible for keeping the neuron healthy. The axonal transport system essentially fast-tracks the rabies virus from the entry wound to the brain, then throughout the rest of the body, where it shuts down organs as it reaches them.

Understanding the axonal transport system could mean better treatment for the 55,000 people in the world who die each year from rabies, most commonly after being bitten by a rabid dog, according to the Centers for Disease Control and Prevention (CDC). Early symptoms may resemble those of the flu, including headache, weakness and fever. “As the disease progresses, more specific symptoms … may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation (increase in saliva), difficulty swallowing and hydrophobia (fear of water),” states the CDC’s website. “Death usually occurs within days of the onset of these symptoms.”

All species of mammals are susceptible to rabies, but domestic dogs and cats who are unvaccinated typically contract rabies from contact with a wild, carnivorous animal such as a bat, raccoon, skunk, fox or coyote.

To help prevent the spread of rabies, owners of dogs, cats and ferrets should vaccinate their pets on a regular schedule. Pets should be kept indoors and supervised whenever they are outside. Spaying or neutering your pets can help keep animal populations under control and reduce the number of pets who end up homeless or unvaccinated. And if you see stray or wild animals in your neighborhood, call animal control, especially if the animal is exhibiting any symptoms of rabies or generally behaving strangely.

“It’s important to recognize the signs of a rabid animal so you can stay away from it,” says pediatrician Jim Sears in this video from CBS’ “The Doctors” series. Symptoms of rabies in animals include foaming at the mouth, aggression and loss of control of the limbs.

But to be on the safe side, it’s best to simply avoid any animals that are strange to you, Sears cautions. “If it’s a stray, if you don’t know the animal, there’s a good chance that it doesn’t have its shots and it’s going to be high-risk for being rabid.”

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